Background: C1q nephropathy has been suggested as a separate disease entity. C1q positivity has also been described in association with nephrotic syndrome (NS) as a potential marker for worse outcome. The aims of this study were to describe the clinical characteristics, laboratory parameters and outcomes of 35 children whose renal histology revealed predominant mesangial C1q deposition and to investigate if the experience at our institution supports the above hypothesis.
Method: Clinical and pathological characteristics of all children whose kidney biopsies showed positive C1q staining were retrospectively recorded. The outcome of children with minimal change nephrotic syndrome (MCNS) and predominant mesangial C1q deposition based on C1q staining was compared with that of a concurrent group of children with MCNS with no such immune staining.
Results: The median age of the patient cohort was 4.5 years (range 6 months to 16 years), 69 % were boys and 88 % presented with nephrotic syndrome (NS). Children with C1q staining and MCNS had more relapses (p = 0.001) and shorter relapse-free periods (p = 0.033) than those with negative immunostaining, but the long-term outcomes were similar in both groups.
Conclusion: Our data do not support C1q nephropathy as a separate diagnostic category. Children with MCNS and mesangial C1q deposition (staining) showed more relapses but no difference in long term renal outcome.